What is listeriosis?

Definition

Listeriosis is a food-borne illness that can lead to death in newborns and in
persons with compromised immune systems. Infants born to women infected with
listeriosis may have meningitis (brain infection) or
bacteremia (bacterial blood infection). Infected infants who
survive may suffer neurological damage and developmental delays. Listeriosis can
cause the death of a fetus of an infected pregnant woman.

Up to 65 percent of deaths from food-borne illnesses in the United States are caused by listeriosis. About twenty-five hundred people become ill with listeriosis per year in the United States, and, of these, five hundred die. The numbers of the infected may be greater, but such cases have not been identified, likely because symptoms were mild.

Causes

Listeriosis is caused by the bacterium
Listeria monocytogenes, a pathogen that
lives in water and soil. It is resistant to refrigeration and is found in
ill-prepared or subsequently contaminated meats and vegetables, particularly in
luncheon meats, hot dogs, soft cheeses, cole slaw, and unpasteurized milk.

Risk Factors

Pregnant women have twenty times the risk of developing listeriosis as others,
according to the Centers for Disease Control and Prevention, and an estimated
one-third of listeriosis cases occur during pregnancy. Other persons at risk are
those with compromised immune systems, such as persons with the acquired immune deficiency
syndrome (AIDS), who have a three hundred times greater risk
for listeriosis compared with healthy persons. In addition, others who are at risk
include persons with cancer, kidney disease, or diabetes; persons who have had an
organ transplant and who take immunosuppressant drugs; persons taking
glucocorticosteroids; and persons age sixty years and older.

Symptoms

Infected persons may present with nausea, vomiting, diarrhea, and fever.
Newborn infants may have jaundice, pneumonia, skin rash, lethargy, and vomiting.
Symptoms may occur anytime from two to seventy days from when the contaminated
food was consumed. Healthy people may have mild symptoms or no symptoms. Pregnant
women may have mild symptoms, but her fetus remains at risk for infection.

Screening and Diagnosis

If listeriosis is suspected, the blood, urine, or feces is screened for L. monocytogenes. Also, a spinal fluid test may be used for screening, and the amniotic fluid of a pregnant woman may be tested.

Treatment and Therapy

Treatment is with antibiotics such as ampicillin.
Infected newborns are also treated with antibiotics.

Prevention and Outcomes

Active measures can help to avoid infection. One should thoroughly cook all meats, wash all vegetables, and avoid unpasteurized milk products. Uncooked meats should be separated from vegetables and other foods during food preparation.

As soon as possible after food preparation, the preparer should wash his or her hands and any cutting boards and knives used to prepare uncooked foods.

Persons at high risk for listeriosis should avoid soft cheese unless the label on the product indicates the cheese was made with pasteurized milk. Deli meat, cold salad, soft cheese, and pâté should be avoided by pregnant women.

Bibliography

Bortolussi, Robert. “Listeriosis: A Primer.” CMAJ: Canadian Medical Association Journal 179 (2008): 795-797.

Cheung, Vincent Y., and Wilma L. Sirkin. “Listeriosis Complicating Pregnancy.” CMAJ: Canadian Medical Association Journal 181 (2009): 821-822.

Khare, Manjiri. “Infectious Disease in Pregnancy.” Current Obstetrics and Gynaecology 15 (2005): 149-156.

U.S. Department of Health and Human Services. National Toxicology Program. “Listeria and Food Poisoning.” Available at http://cerhr.niehs.nih.gov/common/listeria.html.

U.S. National Institutes of Health. “Listeriosis.” Available at http://www.nlm.nih.gov/medlineplus/ency/article/001380.htm.